There is a constant desire to be, by means of a radar, able to detect smaller and smaller objects that are further and further away. One way of achieving these aims is to increase the output power levels of the radar in question. Unfortunately this has several disadvantages, for example in an airborne radar system it is difficult to increase power consumption, as there is a very limited amount of power available. A suitable way of increasing the usability of a radar is thus to increase the sensitivity of the receiver, i.e. to be able to see more with the same output power level, or be able to see the same with a lower output power level.
At the same time there is a desire to reduce the total power consumption of a radar system, this can be achieved in many different ways. One way is to exchange linear voltage regulators with switching regulators, which have a much higher efficiency. Thus by exchanging the power supplies, power consumption of the radar system as a whole can be lowered with a maintained transmitter power output.
Unfortunately these two trends, increased receiver sensitivity and use of switching regulators, are somewhat contradictory. Switching regulators will most commonly produce more disturbances, noise, than their linear counterparts due to one or more switching elements being turned on and off, switched, for regulating purposes, at a fairly high frequency. The switching causes difficult to deal with high frequency components due to a high slew rate in the switching transitions. Receivers with increased sensitivity are unfortunately more susceptible to being influenced by any internally produced electrical noise.
There have been several attempts to come to grips with these contradictory but desirable design trends. For example U.S. Pat. No. 3,760,256 describes a power supply input drive synchronized with the pulse repetition frequency, and U.S. Pat. No. 4,737,899 describes a power supply with an electronic power commutation switch actuated at the recurrence frequency of the pulses produced by the radar. There is still room for improvement.